Nanocomposites films based on soy proteins and montmorillonite processed by casting

IGNACIO ECHEVERRIA; PATRICIA EISENBERG; ADRIANA N MAURI

JOURNAL OF MEMBRANE SCIENCE

ELSEVIER SCIENCE BV

Año: 2014 vol. 449 p. 15 - 26

0376-7388

In this work the effect of montmorillonite (MMT) addition to soy-protein-based films on thephysicochemical properties of the resulting nanocomposites was studied and the structure?functionrelationship of these materials and the changes in phase structures, due to different interactions amongthe material components were analyzed. Flexible nanocomposite films consisting in a soy-protein (SP)matrix supplemented with different concentrations of montmorillonite (MMT) up to 10 g/100 g of SPwere prepared by the casting technique. The resulting films were homogeneous, yellowish, andtransparent and indistinguishable visually from films of pure protein. The process used for filmformation?involving mechanical agitation and ultrasonication, in combination with the intrinsic affinityof MMT for the SPs?favors the dispersion of the clay so as to reach a high degree of intercalation into theprotein matrix with consequent exfoliation of the layers of MMT among the proteins (verified by bothtransmission electron microscopy and X-ray diffraction). The efficient dispersion and distribution of theMMT laminas within the films generated a significant strengthening of the nanolayer that was evident inthe observed resistance to breakage; modulation of elasticity; and decrease in extension, moisturecontent, solubility, and permeability to water vapor. In the presence of MMT, the disulfide bridges in theSPs play a critical role in the stabilization of the protein matrix, whereas in the films composed ofproteins alone the residues capable of participating in hydrogen bonding would be involved in othertypes of highly stabilizing interactions